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1.
Francisella noatunensis subsp. orientalis (Fno) (syn. F. asiatica) is an emergent Gram‐negative facultative intracellular bacterium. Although it is considered one of the most pathogenic bacteria in fish, there are no commercially available treatments or vaccines. The objective of this project was to determine the most efficacious concentration of florfenicol (FFC) [10, 15 or 20 mg FFC kg?1 body weight (bw) per days for 10 days] administered in feed to control experimentally induced infections of Fno in Nile tilapia, Oreochromis niloticus (L.), reared in a recirculating aquaculture system. The cumulative mortality of fish that received 0, 10, 15 or 20 mg FFC kg?1 bw per day was 60, 37, 14 and 16%, respectively. Francisella noatunensis subsp. orientalis genome equivalents were detected in water from all challenged groups with slight reduction in the concentration in the florfenicol‐treated groups 4 days after treatment. The mean LOG of CFU Fno mg?1 spleen was 3–5 and was present in all challenged groups at necropsy 11 days after treatment (21 days after challenge). Results show that florfenicol administered at doses of 15 and 20 mg FFC kg?1 bw per days for 10 days significantly reduced mortality associated with francisellosis in Nile tilapia. 相似文献
2.
Adrin Lpez‐Porras Carolina Elizondo Aida J. Chaves Alvin C. Camus Matt J. Griffin Kirsten Kenelty Samantha Barum Elías Barquero‐Calvo Esteban Soto 《Journal of the World Aquaculture Society》2019,50(3):645-658
Edwardsiella spp., Streptococcus spp., and Francisella noatunensis subsp. orientalis are some of the most important fish pathogens affecting global tilapia, Oreochromis spp., aquaculture. In Costa Rica, the aquaculture industry is dominated by freshwater‐cultured Nile tilapia, Oreochromis niloticus, which are raised in all seven national provinces. At present, little is known regarding the diversity of pathogens present in these facilities, and definitive identification of agents associated with disease outbreaks are rare. To evaluate the prevalence of common bacterial pathogens in these systems, this study used multiplex quantitative polymerase chain reaction (qPCR) assays targeting Edwardsiella, Streptococcus, and Francisella species as a diagnostic and surveillance tool. In 2017, seven different tilapia hatcheries were visited, and 350 fingerlings were subjected to necropsy and molecular diagnostic evaluation. Fish exhibiting gross signs of disease were subjected to histological and microbiological analysis. For the first time, Edwardsiella anguillarum was recovered and molecularly confirmed from diseased tilapia in Costa Rica. In addition, F. noatunensis subsp. orientalis was identified in a region of Costa Rica where it had not been previously reported. 相似文献
3.
Jos Gustavo Ramírez‐Paredes Miguel Angel Mendoza‐Roldan Benjamin Lopez‐Jimena Khalid Shahin Matthijs Metselaar Kim D. Thompson David J. Penman Randolph H. Richards Alexandra Adams 《Journal of fish diseases》2019,42(8):1191-1200
Francisella noatunensis subsp. orientalis is a pathogen of tilapia and other warm‐water fish for which no vaccines are commercially available. In this study, a whole cell formalin‐inactivated vaccine was developed for the first time using the highly virulent isolate STIR‐GUS‐F2f7 and the oil‐based adjuvant Montanide? ISA 763A VG. The efficacy of the vaccine was assessed in red Nile tilapia via intraperitoneal (i.p.) injection using homologous experimental infection and correlates of protection such as seral antibody production and bacterial loads in the spleen. For immunization, fish were i.p. injected with 0.1 ml of the vaccine, the adjuvant alone or PBS. At 840 degree days post‐vaccination, all fish were i.p. injected with 4.0 × 103 CFU/fish of pathogenic bacteria. The RPS at the end of the trial was 100% in the vaccinated group with significantly higher survival than in the adjuvant and control groups. The RPS in the adjuvant group was 42%, and no significant difference was seen in survival between this and the PBS group. Moreover, significantly higher antibody titres in the serum and significantly lower bacterial loads in the spleen were detected in the vaccinated fish by ELISA and qPCR, respectively. These findings highlight the potential of autogenous vaccines for controlling francisellosis in tilapia. 相似文献
4.
Campbell C Pert A Jennifer Mordue Bríd O'Shea Ian R Bricknell 《Aquaculture Research》2012,43(6):799-805
The reproductive success of Lepeophtheirus salmonis settled on host and non‐host fish has been compared. Triplicate single species tanks of Atlantic salmon, marine three‐spined sticklebacks, saithe and Atlantic cod were exposed to 10 adult female L. salmonis per tank (n=30 lice per species). Adult female L. salmonis settlement and egg string production occurred only on salmon and cod, with no egg production occurring on saithe and three‐spined sticklebacks. The number of eggs in egg strings, hatching success of eggs and the survival of all larval stages to the copepodid stage were severely affected by the species of fish on which female L. salmonis had settled. L. salmonis settled on cod produced significantly fewer eggs, lower hatching rates and lower survival rates of larvae than females on Atlantic salmon. The production of egg strings by L. salmonis females infecting cod, which successfully hatch and moult through to the infective copepodid stage, albeit in small numbers, is discussed in terms of the implications to aquaculture and salmon and cod farming scenarios. 相似文献
5.
Francisellosis, caused by the bacterium Francisella piscicida , has become one of the most serious diseases in Atlantic cod production in Norway. The major aim of this study was to determine the distribution of F. piscicida in farmed and wild fish in areas with cod farming along the Norwegian coast, and its occurrence in cod from areas without cod farming. Two real-time PCR assays, targeting the 16S rRNA gene and the FopA gene of F. piscicida , were developed since sensitive and specific diagnostic tools are required for detecting asymptomatic carriers of the bacterium. A total of 422 wild cod from 13 sampling areas and 955 farmed cod from 10 areas along the coast of Norway were examined. Using the real-time polymerase chain reaction (PCR) assays, F. piscicida was detected in wild populations of cod from all counties examined south of Sogn og Fjordane in southern Norway (overall prevalence 13%, n = 221). Wild cod north of Sogn og Fjordane were negative for the bacterium ( n = 201). Farmed cod from most parts of Norway were F. piscicida positive. The apparent absence of the bacterium in wild populations of cod in the northern parts of Norway and its widespread occurrence in wild cod from southern parts of Norway is believed to relate to differences in seawater temperatures. 相似文献
6.
Theeraporn Pulpipat Kuo‐Hua Lin Ying‐Hao Chen Pei‐Chi Wang Shih‐Chu Chen 《Journal of fish diseases》2019,42(5):643-655
Francisella noatunensis subsp. orientalis is a causative agent of systemic granulomatous disease in tilapia. The present study was designed to understand the genetic and phenotypic diversities among Taiwanese Fno isolates obtained from tilapia (n = 17) and green Texas cichlid (Herichthys cyanoguttatus) (n = 1). The enzymatic profiles of the isolates were studied using the API ZYM system. Phylogenetic tree analysis of the 16S rRNA and housekeeping gene and pulsed‐field gel electrophoresis (PFGE) were carried out to determine the genotypic characters of all isolates. The phylogenetic tree showed similarity of 99%–100% nucleotide sequences of 16S rRNA and housekeeping genes compared to the Fno references genes from GenBank database. Comparatively, the results revealed an identical profile of enzymatic and PFGE pattern which was distincted from that of F. philomiragia. To understand the pathogenicity, the isolates were intraperitoneal injected to tilapia the gross lesions were observed concomitant with natural outbreak. Median lethal dose upon Nile tilapia and red tilapia were 9.06 × 103 CFU/fish and 2.08 × 102 CFU/fish, respectively. Thus, our data provide understanding the epidemiology of Taiwanese Fno isolates, and help in development of future control and prevention. 相似文献
7.
B K Gudmundsdottir S Gudmundsdottir S Gudmundsdottir B Magnadottir 《Journal of fish diseases》2014,37(6):511-519
A disease outbreak in farmed Atlantic cod caused by Yersinia ruckeri is reported. Mortality started following vaccination of cod reared in two tanks (A and B). The accumulated mortality reached 1.9% in A and 4.8% in B in the following 30 days when treatment with oxytetracycline was applied. Biochemical and molecular analysis of Y. ruckeri isolates from the cod and other fish species from fresh and marine waters in Iceland revealed a high salinity‐tolerant subgroup of Y. ruckeri serotype O1. Infected fish showed clinical signs comparable with those of Y. ruckeri ‐infected salmonids, with the exception of granuloma formations in infected cod tissues, which is a known response of cod to bacterial infections. Immunohistological examination showed Y. ruckeri antigens in the core of granulomas and the involvement of immune parameters that indicates a strong association between complement and lysozyme killing of bacteria. Experimental infection of cod with a cod isolate induced disease, and the calculated LD50 was 1.7 × 104 CFU per fish. The results suggest that yersiniosis can be spread between populations of freshwater and marine fish. Treatment of infected cod with antibiotic did not eliminate the infection, which can be explained by the immune response of cod producing prolonged granulomatous infection. 相似文献
8.
Wahida Salma Reidar Myklebust Terry M Mayhew Einar Ringø 《Aquaculture Research》2011,42(12):1830-1839
The present investigation addresses whether the midgut (MG) of Atlantic cod (Gadus morhua L.) is an infection route for Vibrio (Listonella) anguillarum serotype 02 β and if Carnobacterium maltaromaticum, a probiotic bacterium, can out‐compete the pathogen and modulate the autochthonous MG microbiota. This was investigated by using an ex vivo method the intestinal sac, utilized previously in studies on Atlantic cod and Atlantic salmon (Salmo salar L.). Exposure of the MG to V. (L.) anguillarum did not reveal any cell damage indicating that the MG does not appear to be an infection route for V. (L.) anguillarum in healthy Atlantic cod. This finding together with previous observations on Atlantic cod and Atlantic salmon indicate that intestine as an infection route might vary between these two species. When the MG was exposed to C. maltaromaticum, no cell damage or cellular disruptions were observed. As budding from the apices of microvilli was observed in all treatments exposed to bacteria, we suggest that budding might be involved in the primary barrier against bacterial infection. However, to clarify this hypothesis, further studies are needed. Exposure of the MG to the probiotics and pathogenic bacteria indicated that C. maltaromaticum, to some extent, is able to out‐compete V. (L.) anguillarum but the topic merits further investigation. Analysis of the MG microbiota after sterile saline solution and bacterial exposure indicates that bacteria related to Staphylococcus sciuri belong to the autochthonous gut microbiota in Atlantic cod. 相似文献
9.
The aquatic orthomyxovirus infectious salmon anaemia virus (ISAV) causes a severe disease in farmed Atlantic salmon, Salmo salar L. Although some ISA outbreaks are caused by horizontal transmission of virus between farms, the source and reservoir of the virus is largely unknown and a wild host has been hypothesized. Atlantic salmon are farmed in open net‐pens, allowing transmission of pathogens from wild fish and the surrounding environment to the farmed fish. In this study, a large number of fish species were investigated for ISAV host potential. For orthomyxoviruses, a specific receptor binding is the first requirement for infection; thus, the fish species were investigated for the presence of the ISAV receptor. The receptor was found to be widely distributed across the fish species. All salmonids expressed the receptor. However, only some of the cod‐like and perch‐like fish did, and all flat fish were negative. In the majority of the positive species, the receptor was found on endothelial cells and/or on red blood cells. The study forms a basis for further investigations and opens up the possibility for screening species to determine whether a wild host of ISAV exists. 相似文献
10.
Temperature controls important physiological processes in fish and determines aspects of their niches. In an effort to inform selective fishing and spatiotemporal management in the U.S. Northeast Multispecies fishery, we used 16 years of data from the Northeast Fisheries Science Center Spring and Fall Scientific Trawl Surveys to determine if bottom temperature can be used to differentiate the distribution of Atlantic cod (Gadus morhua) from other species within the fishery management plan (FMP). We identified two separate regimes in spring temperatures and used empirical cumulative distribution functions to calculate biomass availability by temperature for each species. We applied a bagged approach to find optimum thermal threshold values that maximize the difference in cod biomass from each of the other species. For our study area, 38% to 54% of the species considered were well separated from cod by temperature in spring, whereas only 17% were separable in the fall. This study suggests that temperature targeting can be used seasonally to separate cod from many other species in the FMP including top catches and no‐retention species. The use of temperature targeting may allow fishermen to better meet multiple quotas while avoiding choke species. Our results also suggested increasing thermal overlap between cod and species inhabiting higher median temperatures (e.g., spiny dogfish, Squalus acanthias) under the current warming temperature regime. These results indicate that the ability to selectively fish in the US Northeast Multispecies fishery will become more difficult under a warming ocean. 相似文献
11.
Sayuj Poudyal Theeraporn Pulpipat Pei-Chi Wang Shih-Chu Chen 《Journal of fish diseases》2020,43(9):1097-1106
Francisella orientalis is a highly virulent, emerging bacterium that causes mass mortalities in tilapia. This pathogen also affects numerous other warm-water fish species, including three-line grunt, hybrid striped bass and various ornamental fish. This study sheds light on two new species of fish that are susceptible to F. orientalis. Asian seabass and largemouth bass showed variable levels of susceptibility in a bacterial challenge experiment. After intraperitoneally injected with a dose of 106 CFU/fish, a total of 64.28% and 21.42% mortalities were obtained in Asian seabass and largemouth bass, respectively. Meanwhile, Nile tilapia showed acute mortality of 100%. All fish showed typical lesions of francisellosis, including multifocal granulomas in the spleen and head kidney. Immunohistochemical analysis revealed strong positive signals inside the granulomas of all fish. The bacterial recovery in solid media from infected fish was highest in Nile tilapia (85.71%), followed by Asian seabass (35.71%) and largemouth bass (21.42%). PCR results tested 100% positive for Nile tilapia, and 78.57% and 21.42% for Asian seabass and largemouth bass, respectively. In conclusion, Asian seabass and largemouth bass are susceptible to this pathogen, which warrants new management strategies when employing predation polyculture systems of these species with tilapia. 相似文献
12.
- The Gilbert Bay Marine Protected Area (MPA), Labrador, was created in 2005 to protect a resident, locally adapted population of Atlantic cod and its habitat. Twenty years of monitoring has shown a 90% decline in this bay-cod population since the creation of the MPA.
- The decline of large commercial-sized cod in the bay was accompanied with increases in the abundance of other fish species, including rock cod (Gadus macrocephalus ogac), sculpin (Myoxocephlalus scorpius), and winter flounder (Pseudopleuronectes americanus), suggesting loss of strong top-down community control.
- These changes suggest a positive feedback mechanism leading to a fish community tipping point, which could severely impact the recovery potential of the protected Atlantic cod population in the MPA.
- We suggest that managers should be including this possibility in their management decisions for the Gilbert Bay MPA.
13.
Gut‐associated bacteria of fish are known to produce enzymes which aid in digestion. The presence and activities of these bacteria in cold‐water fishes like Atlantic cod are less known. Therefore, we have characterized the activities of extracellular enzymes of GP21 (Pseudomonas sp.) and GP12 (Psychrobacter sp.), two bacteria isolated from the gastrointestinal tract of Atlantic cod. Additionally, we examined if these bacteria when delivered through feeds could influence the activity of selected intestinal enzymes. GP21 was able to produce amylase, chitinase, cellulase and protease, whereas GP12 could produce only chitinase and protease. These enzymes were produced extracellularly and they were found to be catalytically active at acidic conditions (pH 2–5) and at temperatures ranging from 15 to 30 °C. Orally delivered bacteria could possibly influence the activity of intestinal enzymes after 40 days, rather than after 20 days of feeding. Thus GP21 and GP12, the potential probiotic organisms, could support digestion in Atlantic cod. 相似文献
14.
Effect of hydrogen peroxide as treatment for amoebic gill disease in Atlantic salmon (Salmo salar L.) in different temperatures 
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下载免费PDF全文 Kristine Hov Martinsen Audur Thorisdottir Marie Lillehammer 《Aquaculture Research》2018,49(5):1733-1739
Amoebic gill disease (AGD) is a pathogenic disease in salmonids caused by Neoparamoeba perurans. Treatment of AGD infection has been through freshwater bathing of the fish. However, as the availability of fresh water is often limited, hydrogen peroxide has been introduced as an alternative treatment. This study investigated the effect of hydrogen peroxide as treatment for AGD‐infected salmon (Salmo salar L.,) at different seawater temperatures and hydrogen peroxide dosages. In total, 600 fish were challenged with N. perurans and the severity of the AGD infection was measured using a gill score scale. After challenge and disease development, the fish were distributed into 12 tanks. The treatment was performed at different seawater temperatures (8°C, 12°C, 17°C) using different hydrogen peroxide doses. Each temperature included an untreated control group. Linear models were used to analyse gill score. A significant effect of treatment was found (?0.68 ± 0.05) regardless of dose and temperature, suggesting that hydrogen peroxide was effective in treating AGD. When the model included dose, a negative linear relationship between dose and gill score was found. The study proved that treatment of AGD with hydrogen peroxide was successful, as gills partially recovered following treatment and further disease development was delayed. 相似文献
15.
A method to evaluate protein quality using in vivo methods was developed for larval fish. FluoSpheres® fluorescent microspheres (10 μm) were incorporated into two test diets, our standard zein microdiet (ZMD) and a microdiet with identical ingredients except for the replacement of high quality fish meal with the same product cooked for 24 h at 80 °C (ZMD-CF). Several trials were performed to design a reliable method to test digestibility using FluoSpheres® as a marker. The developed in vivo technique was tested on 35 days posthatch (dph) larval Atlantic cod ( Gadus morhua L.) and two tropical fish species in the early juvenile stage. The method took into account loss of total protein to the faecal pellet and water column. Apparent digestibility of protein in larval cod fed ZMD was significantly higher than that of larvae fed ZMD-CF ( P < 0.05). A growth study to validate differences between the two diets showed significant differences in growth and survival of larvae fed ZMD versus ZMD-CF ( P < 0.05). Further validation of our results was indicated through the use of a pH-stat method using enzymes extracted from 35 dph larval cod guts. This novel technique will be advantageous for researchers to evaluate feed ingredients for larval marine fish and is adaptable to many different areas of larval fish nutrition. 相似文献
16.
There is inconsistent evidence of resistance of Atlantic salmon, Salmo salar L., to amoebic gill disease (AGD). Here, evidence is presented that demonstrates that Atlantic salmon exposed and subsequently challenged with AGD are more resistant than naïve control fish. Seventy‐three per cent of Atlantic salmon previously exposed to AGD survived to day 35 post‐challenge compared with 26% exposed to Neoparamoeba sp. for the first time, yet the gill pathology of surviving naïve control or previously exposed fish was not significantly different. Development of resistance to AGD is associated with anti‐Neoparamoeba sp. antibodies that were detectable in serum of 50% of surviving Atlantic salmon previously exposed to AGD. However, anti‐Neoparamoeba sp. antibodies were not detectable in cutaneous mucus of resistant fish. Increased resistance of Atlantic salmon after secondary Neoparamoeba sp. infection and detection of specific serum antibodies provides support for the development of a vaccine for AGD. 相似文献
17.
18.
Previous work in our laboratory defined a method of inducing laboratory‐based amoebic gill disease (AGD) in Atlantic salmon, Salmo salar L. Gills of AGD‐affected fish were scraped and the debris placed into fish‐holding systems, eliciting AGD in naïve Atlantic salmon. While this method is consistently successful in inducing AGD, variability in the kinetics and severity of infections has been observed. It is believed that the infections are influenced by inherently variable viability of post‐harvest amoeba trophozoites. Here, a new method of experimental induction of AGD is presented that redefines the infection model including the minimum infective dose. Amoebae were partially purified from the gills of AGD‐affected Atlantic salmon. Trophozoites were characterized by light microscopy and immunocytochemistry and designated Neoparamoeba sp., possibly Neoparamoeba pemaquidensis. Cells were placed into experimental infection systems ranging in concentration from 0 to 500 cells L?1. AGD was detected by gross and histological examination in fish held in all systems inoculated with amoebae. The number of gross and histological AGD lesions per gill was proportional to the inoculating concentration of amoebae indicating that the severity of disease is a function of amoeba density in the water column. The implications of these observations are discussed in the context of the existing AGD literature base as well as Atlantic salmon farming in south‐eastern Tasmania. 相似文献
19.
Tatiana N. Ageeva Ragnar L. Olsen Sjurdur Joensen Margrethe Esaiassen 《Journal Of Aquatic Food Product Technology》2018,27(4):477-485
Fresh Atlantic cod is available in large amounts in Norway during the first 5 months of the year. Live-storage of cod may extend the marketing period of fresh cod products throughout the year. In addition, this concept makes pre-rigor processing possible. The main problem of keeping wild cod in captivity is that it does not easily accept formulated dry feed. The purpose of this study was, therefore, to investigate how long-term live-storage of mature Atlantic cod in the absence of feed (79 days) affects the onset and development of rigor mortis, as well as fillet quality by assessing hardness and water-holding capacity of the muscle, pH, protein, and water content. The results showed that starvation of Atlantic cod for 23 days reduces the pre-rigor time from 29 to 17 h. Further starvation did not decrease this period significantly, suggesting that live-stored cod deprived of feed for 79 days may still be industrially processed before the onset of rigor mortis. More than 51 days of starvation reduced protein concentration and increased water content of the muscle. After 51 days, the muscle texture was softer than in fish starved for a shorter period. 相似文献
20.
Wild and farmed Atlantic salmon ( Salmo salar L.) and Atlantic cod ( Gadus morhua L.) were collected to assess changes in mercury with size in wild vs. farmed fish. Mercury concentrations were compared with Health Canada and United States Environmental Protection Agency consumption guidelines. Lipid dilution of mercury was examined by comparing lipid-extracted (LE) and non-lipid-extracted (NLE) flesh samples in both farmed and wild fish. Mercury concentrations in the flesh and liver of farmed salmon were significantly lower than concentrations in wild salmon of similar fork length ( P <0.001), possibly due to growth dilution in rapidly growing farmed fish. Mercury concentrations were higher in LE tissue compared with NLE ( P <0.05), suggesting lipid dilution of mercury in farmed fish with a high lipid content. Farmed cod, which do not grow more rapidly than wild cod, did not have significantly different flesh and liver concentrations compared with wild cod of similar fork length ( P >0.05). Between species of farmed fish, cod had significantly higher mercury concentrations than salmon ( P <0.05), but neither farmed nor wild salmon mercury concentrations exceeded federal consumption guidelines. These results suggest that rapid growth rates and a high lipid content may play important roles in regulating concentrations of contaminants such as mercury. 相似文献